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119 lines
3.3 KiB
C++
119 lines
3.3 KiB
C++
#pragma once
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///@file
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#include "store-api.hh"
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namespace nix {
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typedef std::unordered_map<StorePath, std::unordered_set<std::string>> Roots;
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struct GCOptions
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{
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/**
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* Garbage collector operation:
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*
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* - `gcReturnLive`: return the set of paths reachable from
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* (i.e. in the closure of) the roots.
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*
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* - `gcReturnDead`: return the set of paths not reachable from
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* the roots.
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*
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* - `gcDeleteDead`: actually delete the latter set.
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*
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* - `gcDeleteSpecific`: delete the paths listed in
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* `pathsToDelete`, insofar as they are not reachable.
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*/
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typedef enum {
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gcReturnLive,
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gcReturnDead,
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gcDeleteDead,
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gcDeleteSpecific,
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} GCAction;
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GCAction action{gcDeleteDead};
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/**
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* If `ignoreLiveness` is set, then reachability from the roots is
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* ignored (dangerous!). However, the paths must still be
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* unreferenced *within* the store (i.e., there can be no other
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* store paths that depend on them).
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*/
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bool ignoreLiveness{false};
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/**
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* For `gcDeleteSpecific`, the paths to delete.
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*/
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StorePathSet pathsToDelete;
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/**
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* Stop after at least `maxFreed` bytes have been freed.
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*/
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uint64_t maxFreed{std::numeric_limits<uint64_t>::max()};
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};
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struct GCResults
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{
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/**
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* Depending on the action, the GC roots, or the paths that would
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* be or have been deleted.
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*/
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PathSet paths;
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/**
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* For `gcReturnDead`, `gcDeleteDead` and `gcDeleteSpecific`, the
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* number of bytes that would be or was freed.
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*/
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uint64_t bytesFreed = 0;
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};
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/**
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* Mix-in class for \ref Store "stores" which expose a notion of garbage
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* collection.
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*
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* Garbage collection will allow deleting paths which are not
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* transitively "rooted".
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*
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* The notion of GC roots actually not part of this class.
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*
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* - The base `Store` class has `Store::addTempRoot()` because for a store
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* that doesn't support garbage collection at all, a temporary GC root is
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* safely implementable as no-op.
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*
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* @todo actually this is not so good because stores are *views*.
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* Some views have only a no-op temp roots even though others to the
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* same store allow triggering GC. For instance one can't add a root
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* over ssh, but that doesn't prevent someone from gc-ing that store
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* accesed via SSH locally).
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*
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* - The derived `LocalFSStore` class has `LocalFSStore::addPermRoot`,
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* which is not part of this class because it relies on the notion of
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* an ambient file system. There are stores (`ssh-ng://`, for one),
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* that *do* support garbage collection but *don't* expose any file
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* system, and `LocalFSStore::addPermRoot` thus does not make sense
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* for them.
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*/
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struct GcStore : public virtual Store
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{
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inline static std::string operationName = "Garbage collection";
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/**
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* Find the roots of the garbage collector. Each root is a pair
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* `(link, storepath)` where `link` is the path of the symlink
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* outside of the Nix store that point to `storePath`. If
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* `censor` is true, privacy-sensitive information about roots
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* found in `/proc` is censored.
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*/
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virtual Roots findRoots(bool censor) = 0;
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/**
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* Perform a garbage collection.
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*/
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virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
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};
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}
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